- Strengthens wall: masonry (CMU, grout, mortar) is good in compression, but bad in tension – reinforcement is great in tension.
- Reinforced cells must be grouted to bind reinforcement to CMU .
- Generally needed at exterior walls.
- Reinforced bars are typically ASTM A615, fy = 60ksi; they can be ASTM A706 grade if welding is required.
- Contractor would prefer to use 2 smaller bars vs 1 larger bar .
- Bar sizes need to consider laps. For a portion of the wall height, there will be twice the reinforcement in each cell.
- If larger bars are required and laps will not fit, use reinforcing couplers. The couplers must be designed for at least 125% of the yield strength of the bar.
- Bar sizes are limited by the following criteria: the area of reinforcing must be less than or equal to 4% of the cell area (8% at laps); the bar diameter must be less than or equal to 1/8 of the least nominal member dimension; and the bar can be no larger than a #9.
Threaded rebar couplers to eliminate laps in 8” CMU wall
- Size CMU appropriately so rebar fit into cell with proper grout cover.
(2) #8 in a 8” CMU. There is not enough clearance for proper grout cover. This could lead to diminished wall strength and cracks in the CMU.